1. Technical Field
The invention concerns a method of establishing a connection via a communications network to a called terminal which is geographically located in the area of two or more local line networks, as well as an exchange for a communications network and a service control point for connection to one or to several exchanges of a communications network.
2. Discussion of Related Art
Presently the usual methods of establishing a connection will route a call request to the subscriber station by means of a call number of the called subscriber which is entered therein. In this case the call number provides the path through the communications network and is evaluated step by step along the path through the communications network, i.e. it first addresses for example the local exchange area, then the subscriber""s exchange, and then the station of the called subscriber within the numbering range of the subscriber""s exchange.
However all of these methods of establishing a connection fail if the local line networks of different network operators share the calling range in a subscriber line area but the requirement for call number portability still remains. In this case call number portability means that a subscriber is able to change local line network operators within his subscriber line area and can take his call number with him to the new network operator. The result is that there is no longer a fixed association between the local line network and the call number of a called subscriber, which can be identified with the call number.
The invention now starts with a method of establishing a connection in a deregulated network environment, as proposed in the report xe2x80x9cHigh level service description for number portabilityxe2x80x9d of the xe2x80x9cPublic Network Operatorsxe2x80x94Interest Groupxe2x80x9d, Jun. 29, 1994 as a possible solution for achieving call number portability in the United Kingdom (UK).
Call number portability is achieved by translating the call number by means of call forwarding or by means of an IN service (IN=Intelligent Network). If a subscriber changes from one network operator to a second network operator within a local exchange area and wishes to take his call number with him, call forwarding is installed as a service in the local line network of the first network operator. If this service identifies a call request with this call number, the call request is rerouted to the local line network of the second network operator. This rerouting takes place by entering a new call number into the call request instead of the original call number, which addresses the subscriber as a subscriber of the local line network of the second network operator.
In this case the relocated call number and the local line network to which a call request with this call number is to be routed, must be entered into a data base by the network operator. The call forwarding service is controlled by the data from this data base.
A disadvantage of this solution is that this data base which assists the forwarding service must be continuously updated by the network operator. If the data base updating is delayed, the concerned subscriber can no longer be reached.
Further drawbacks result when the portability of call numbers is demanded to a greater extent and therefore a large number of forwarding services are provided by a communications network. All of these forwarding services must then be synchronized by a master data base. This causes a large expense.
The task of the invention is to present an alternative method of establishing a connection in a communications network, to a terminal that is located in the area of two or more local line networks.
According to a first aspect of the invention, a method of establishing a connection through a communications network to a called terminal located in the geographical area of two or more local line networks, wherein a calling terminal requests a connection to the called terminal by means of a call request which is provided with a called number assigned to the called terminal, and wherein that of the two or more local line networks via which the called terminal can be reached is determined for the establishment of the connection, characterized in that the local line network via which the called terminal can be reached is determined by means of a learning procedure using the called number.
According to a second aspect of the invention, an exchange for a communications network with a routing guidance device for controlling the establishment of a connection via the communications network to the called terminal, wherein the routing guidance device is provided with reception means for receiving a call request with a called number assigned to the called terminal, and with control means that are designed so that if the called terminal is assigned to a subscriber line area, and its call number area is shared by two or more local line networks, that of the two or more local line networks via which the called terminal can be reached is determined for the establishment of the connection, characterized in that the control means are designed so that the local line network via which the called terminal can be reached is determined by means of a learning procedure using the called number.
According to a third aspect of the invention, a service control point for connection to one or to several exchanges of a communications network, with a receiving unit for receiving a call request, with a called number assigned to a called terminal, and with control means that are designed so that if the called terminal is assigned to a subscriber line area, and its calling range is shared by two or more local line networks of different network operators, they determine that of the two or more local line networks via which the called terminal can be reached, characterized in that the control means are designed so that the local line network via which the called terminal can be reached is determined by means of a learning procedure using the called number.
The basic idea of the invention is that when a connection is established, the destination local line network is no longer determined on the basis of the numbering plan of the called terminal""s call number, but by a learning procedure using the called terminal""s call number. In that case the number of the called terminal is generally a very logic address which is addressed by a terminal or by a subscriber assigned to this terminal.
Thus the assignment of the call number of a terminal to a local line network no longer needs to be entered into a data base by the network operator. Nor is any explicit updating of said data base required any longer. Rather the method of establishing a connection provides that the local line network which is assigned to a call number is learned in accordance with the learning procedure.
Further advantages of the invention result when a communications network provides a number of forwarding services. In that case the provision of a central master data base is no longer required. The services learn in a rather decentralized manner the assignment of local line networks to the incoming call numbers they receive. Based on this decentralized learning procedure, the expense of providing a central master data base and the expense of the communication for synchronizing the distributed data bases via the master data base are absent.
Since a central component is omitted, namely the master data base, the invention has increased fail-safety. A failure of the central master data base would affect the entire communications network, while the failure of a learning-capable node only affects one partial network in a large number of partial networks.
However it is also possible to support the learning procedure with a master data base when using the method of establishing a connection according to the invention. This leads to an acceleration of the learning procedure.
Another advantage is that the method of the invention to establish a connection can be directly integrated into the routing guidance of exchanges and thus the cost of introducing this method of establishing a connection is low.